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(No Model.

0. G. CARROLL. APPARATUS FOR MELTING AND GAST ING METALS.

No. 480,232. Patented Aug. 2, 1892.

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WITNESSES:

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' UNITED STATES PATENT @FFICE.

CRAFT O. CARROLL, OF NEW YORK, N. Y.

APPARATUS FOR MELTING AND CASTING METALS.

SPECIFICATION forming part of Letters Patent No. 480,232, dated August2, 1892.

I Application filed September 1891. Serial No. 404,890. (No model.)

To all whom it may concern.-

Be it known that I, CRAFT O. CARROLL, a citizen of the United States,and a resident of the city and county of New York, in the State of NewYork, haveinvented certain new and useful Improvements in Apparatus forMelting and Casting Metals, of which the following is a. specification,such. as will enable others skilled in the art to which it appertains tomake and use the same.

My invention relates to that class of melting and casting apparatus inwhich the metal is fused in acrucible and introduced into the mold bymeans of pneumatic pressure, and more particularly to those designed foruse by dentists in casting dental plates, crowns, and bridges, and is animprovement on the apparatus shown and described in United StatesLetters Patent No. 382,087, granted upon the application of J. E. HolmesMay 1, 1888.

The object of my invention is to do away with many of the difficultiesheretofore experienced with this classof devices, and this I accomplishby means of an apparatus extremely simple in construction and easy ofoperation, which is fully disclosed in the following specification, ofwhich the accompanying drawings form a part, wherein similar numerals ofreference designatelike or equivalent parts wherever found throughoutthe several views, and in which- Figure 1 is a view in central verticalsection of my improved melting and casting apparatus; Fig. 2, a view ofa detail thereof, parts being broken away; and Fig. 3, a viewofthepneumaticcastingdeviceconnectedwith the crucible, the latter beingshown in central vertical section.

Referring to the drawings, the numeral 1 designates the burner,preferably of metal and of annular form, as shown, having a centralchamber 2, open at the top and provided with a central hole in thebottom, which chamher 2 is surrounded by an outer circular chamher 3,closed at the bottom and provided at the top with a covering-ring 4,having a series of holes 5, beneath which is placed a ring of wire-gauze6. Entering this circular chamber 3 at any convenient point is a pipe 7,provided with air-holes S and an interior gaspipe 9, through which gasand air are fed to the burner, as hereinafter more particularly setforth.

The ring at, which forms the top of the circular chamber 3 of the burner1, is provided with a number of upwardly-projecting studs 10, upon whichrest a hood or cover 11, preferably of the conical form shown andconsisting of a metallic outer casing 12, having an inner lining 13 ofasbestus or other nonconducting material and having a vent-hole 14c andpeep-hole 15, which latter may, if desired, be provided with a coveringof mica or other suitable substance.

Within the central chamber 2 of the burner 7 1 is placed a mold 16 ofany, desired form of construction, but preferably of that shown, theflask consisting of two parts 17 and 18, held togetherby screws 19 atthe bottom and by a washer 20, fitting around the neck 21 at i the topand having a filling 22 of plaster-ofparis or other suitable material,through which a duct 23, through which the molten metal is introduced,passes from the neck 21 to the metal-chamber 24.

Upon the top of the mold 17 is placed a crucible 25, preferably of theform shown, made of soapstone or other suitable material and having inthe bot-tom thereof a downwardly-depending plug 26, which may be formedintegrally therewith, but which is preferably formed of metal andattached thereto by a screw-thread, and this plug 26 is made of suchsize as to fit tightly into the neck of the mold-flask, and inconnection with a soft washer 27, preferably of asbestus, to form anair-tight joint therewith and running through this plug 26 and thebottom of the crucible is a hole or passage 27, which registers with andforms a continuation of the duct 23 in the filling of the mold-flask,which leads to the metal chamber 24 thereof.

The numeral 28, Fig. 3, designates a plug, of soapstone or othersuitable material, of such size as to form an air-tight stopper for thetop of the crucible 25 provided with a central hole into which is fitteda tube 29, connected by means of a flexible rubber tube with a pneumaticbulb 31, by which air may be forced into the interior of the crucible25.

The operation of the device is as follows: The mold having been properlyprepared and fastened together by means of the screws 19 and Washer 20,or in any other desired manner, the same is placed in posit-ion in thecentral chamber 2 of the burner 1, as shown in Fig. 1. The asbestuswasher 27 is then placed upon the plug 26 of the crucible 25, which isthen forced tightly down into the neck of the mold-flask, when thecrucible will be in position to be filled with the appropriate quantityof metal, after which, gas being admitted through the pipe 9 and ignitedat the holes 5 at the top of the burner, the hood or cover 12 is placedin position over the crucible 25, as shown in Fig. 1, and the parts areallowed to remain in that position until the contents of the cruciblehave fully melted. The gas with which the burner is fed, flowing intothe pipe 7 through the pipe 9, draws with it a large quantity of airthrough the holes 8, and, this being mingled thoroughly with the gas inpassing through the chamber 3 and wire-gauze 5, each of the holes 5becomes a Bunsen burner, and the flames being directed toward thecenterof the hood by reason of the conical shape thereof, and theair-current which is drawn in under such hood or cover 12, causes greatheat to be concentrated upon the crucible 25, and the metal therein issoon melted at the same time a sufficient quantity of the heat generatedis directed against the top of the mold, which projects, as shown,slightly above the top of the burner 1 to heat the same to the degreerequired to obtain a perfect casting. The mold and also the jointbetween the same and the crucible being air-tight, it is impossible forany of the molten metal to flow into the mold untiltheoperatorsodesires;butwhen the metalis in the propel-state, which can be told by lookinginto the crucible through the peephole 15, the cover or hood 12 isremoved and the plug 28, connected with the pneumatic bulb 31, is fittedtightly into the top of the crucible, as shown in Fig. 3 and in dottedlines in Fig. 1, and by simply forcing air through the bulb bycompressing the same in the usual manner the molten metal is then drivenby the pneumatic pressure thus obtained into the inetal-chamber of themold, from which the casing may be removed in the usual manner when thesame has sufliciently cooled.

The process of forming the metal chamber of'the mold, the ductscommunicating therewith, of placing the teeth therein, and of removingthe casting is well known and is preferably the same as that describedin the United States patent hereinbefore referred to, although any formof mold desired may be used.

It is evident that burners other than those suitable for gas may beused, and that many other changes in the construction, combination, andarrangement of parts of my improved melting and casting apparatus may bemade without departing from the scope of my invention, and I do notlimit myself to any particular form thereof; but

Having fully described my invention, its construction and operation,what I claim, and desire to secure by Letters Patent, is

1. The combination,withan annular burner, of a mold-flask supportedtherein so that the flame-openings of the burner are at or near the topof the flask, a crucible mounted upon the mold-flask and incommunication with the metal-chamber of the mold, and a removableconical hood or cover mounted upon the burner and inclosing the flame-openings thereof and the crucible in such manner as to direct the flamefrom the burner-openings upon the crucible, substantially as shown anddescribed.

2. In an apparatus for melting and casting metals for dental orotherpurposes, the combination, with an annular burner having flameopeningsin the top thereof,of a mold-flask supported therein so that the top ofthe burneris at or near the top of the flask, a crucible mounted on thetop of the flask and in communication with the metal-chamber thereof, aconical removable hood or cover mounted upon the burner and inclosingthe flame-openings thereof, so as to direct the flame upon the crucible,and means for forcing the molten metal from the crucible into themetal-chamber of the mold-flask after the hood or cover has beenremoved, substantially as shown and described.

3. In an apparatus for melting and casting metals for dental or otherpurposes, the combination, with an annular burner, of a moldflasksupported therein in such manner that the flame-openings of the burnerare at or near the top of the mold-flask, a crucible supported on themold-flask, provided with a duct or passage through the bottom thereofwhich communicates with a duct or passage in the mold-flask leading tothe chamber thereof, the joint between the crucible and the moldflaskbeing air-tight, and means for forcing the molten metal from thecrucible into the metal-chamber of the flask, consisting of a flexibletube and pneumatic bulb, substantially as shown and described.

Signed at the city and countyof New York, in the State of New York, this2d day of September, A. D. 1891.

CRAFT C. CARROLL.

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